Mutation trend analysis of signature and non-signature amino acid residues in the functional domains of the proteins of 2009 H1N1pdm during the influenza pandemic in 2009.

<p>Note: the number in brackets indicates the percent (%) of sequences with the mutated amino acid in total number of the sequences collected in the period; ‘-’ means unavailable in non-H1N1 virus.</p

Comparison of the amino acid signatures in the proteins of 2009 H1N1pdm with those in human, swine, and avian IAVs, as well as those causing past influenza pandemics.

<p>Note: Only the dominant residues were listed. The human-like amino acid signatures in the 2009 H1N1pdm were highlighted in bold and italic.</p

The identity of amino acid signatures in the proteins of pandemic IAVs and human, swine, and avian IAVs.

<p>The identity of amino acid signatures in the proteins of pandemic IAVs and human, swine, and avian IAVs.</p

Schematic representation of the functional domains with mutated residues in the 2009 H1N1pdm proteins.

<p><b>Left panels</b>: bird's eye view of protein structures of 2009 H1N1pdm collected at the pre-epidemic period in 2009; <b>Middle panels</b>: close-up view of the mutated amino acid residues in proteins of 2009 H1N1pdm collected at the pre-epidemic period in 2009; <b>Right panels</b>: close-up view of the mutated amino acid residues in proteins of 2009 H1N1pdm collected at the late period in 2009. The amino acid numberings were based on influenza virus A/Puerto Rico/8/1934 (H1N1) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0009549#pone.0009549-Chen1" target="_blank">[6]</a>. The residues in viruses collected in the pre-epidemic period are colored in red, and those in viruses collected in the late period are colored in yellow. <b>A–C:</b> NP trimer and monomer. <b>D–F:</b> NA tetramer and monomer. Drug target domain (DTD) is highlighted in dark blue. H260 [274 in A/Vietnam/1203/04(H5N1)] is a critical residue for the NA inhibitor, oseltamivir. NA H274Y mutation results in resistance of 2009 H1N1pdm and other influenza viruses to oseltamivir. <b>G–I</b>: HA trimer and monomer. Receptor binding domain (RBD) was highlighted in wheat color, while other part is in green color. <b>J–L</b>: Dimer and monomer of effector domain (ED) in NS1.</p